Method for measuring critical dimensions

Abstract

A method of measuring a critical dimension is provided. The method includes providing a substrate; forming a photoresist layer on the substrate, wherein the photoresist layer includes a solvent, an unactivated polymer resin, a photoacid generator, and a photosensitizer generator; exposing the photoresist layer to a radiation source at a first wavelength; exposing the photoresist layer to a radiation source at a second wavelength different from the first wavelength; heating the photoresist layer; continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point after forming the photoresist layer on the substrate to a second time point after heating the photoresist layer to obtain a concentration profile of the volatile byproduct; and obtaining the critical dimension based on an integrated difference of the concentration profile between the first time point and the second time point; wherein the photosensitizer generator is sensitive to the second wavelength and the photoacid generator is not sensitive to the second wavelength.

Description

Technical Field

[0001] This application claims priority to U.S. Patent Applications Nos. 17 / 584,585 and 17 / 584,889 (with the earliest priority date being January 26, 2022), the contents of which are incorporated herein by reference in their entirety.

[0002] This disclosure relates to a method for measuring a critical dimension. In particular, it relates to a non-destructive method for measuring a critical dimension. Background Technology

[0003] Semiconductor components are used in various electronic applications, such as personal computers, mobile phones, digital cameras, and other electronic devices. The size of semiconductor components is gradually shrinking to meet the increasing demands for computing power. However, this shrinking process introduces new and increasingly complex problems. Therefore, the challenges of improving quality, yield, performance, and reliability, while reducing complexity, continue.

[0004] The above description of "prior art" provides background information only and does not acknowledge that the above description of "prior art" discloses the subject matter of this disclosure. It does not constitute prior art to this disclosure, and no description of the above "prior art" should be considered part of this case. Summary of the Invention

[0005] One embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate; monitoring a volatile byproduct generated from the photoresist layer to obtain a first quantity of the volatile byproduct; exposing the photoresist layer to a radiation source; monitoring the volatile byproduct generated from the photoresist layer to obtain a second quantity of the volatile byproduct; and obtaining the critical size based on the difference between the first quantity and the second quantity of the volatile byproduct.

[0006] Another embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate; exposing the photoresist layer to a radiation source; heating the photoresist layer; continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point at which the photoresist layer is formed on the substrate to a second time point after the photoresist layer is heated to obtain a concentration curve of the volatile byproduct; and obtaining the critical size based on the integral difference of the concentration curve between the first time point and the second time point.

[0007] Another embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate, wherein the photoresist layer includes a solvent, an unactivated polymer resin, a photoacid generator, and a photosensitizer generator; exposing the photoresist to a radiation source at a first wavelength; exposing the photoresist to a radiation source at a second wavelength, the second wavelength being different from the first wavelength; heating the photoresist layer; continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point after the formation of the photoresist layer on the substrate to a second time point after heating the photoresist layer to obtain a concentration curve of the volatile byproduct; and obtaining the critical size based on the integral difference of the concentration curve between the first time point and the second time point. The photosensitizer generator is sensitive to the second wavelength, while the photoacid generator is not sensitive to the second wavelength.

[0008] Because of the design of the critical dimension measurement method disclosed herein, the critical dimension of the actual pattern can be measured without any damage from the volatile byproducts generated from the photoresist layer. Furthermore, there is no need for dummy marks used for metrology. This saves the area previously occupied by dummy marks used for metrology. Therefore, more physical space can be provided for multiple functional circuits, thereby reducing costs.

[0009] The foregoing has provided a fairly broad overview of the technical features and advantages of this disclosure, enabling a better understanding of the detailed description that follows. Other technical features and advantages constituting the subject matter of the claims will be described below. Those skilled in the art to which this disclosure pertains will understand that the concepts and specific embodiments disclosed below can be readily utilized to achieve the same purpose as this disclosure by modifying or designing other structures or processes. Those skilled in the art will also understand that such equivalent constructions cannot depart from the spirit and scope of this disclosure as defined by the appended claims. Attached Figure Description

[0010] When with attachment Figure 1 When reading this document, the best understanding of all aspects of this disclosure can be obtained from the following detailed description. It should be understood that, according to industry standard practice, the various features are not drawn to scale. In fact, the dimensions of the various features can be increased or decreased arbitrarily for clarity of discussion.

[0011] Figure 1 This is a flowchart illustrating a method for measuring the critical dimensions of a semiconductor device according to an embodiment of the present disclosure.

[0012] Figures 2 to 5 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to an embodiment of the present disclosure.

[0013] Figure 6 This is a concentration distribution diagram illustrating an embodiment of the present disclosure. Figure 5 The photoacid concentration distribution is shown in the example.

[0014] Figure 7 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to an embodiment of the present disclosure.

[0015] Figure 8 This is a concentration distribution diagram illustrating an embodiment of the present disclosure. Figure 7 The photoacid concentration distribution is shown in the example.

[0016] Figure 9 This is a schematic diagram illustrating the concentration curve of volatile byproducts generated from a photoresist layer, measured by a gas analyzer, according to an embodiment of this disclosure.

[0017] Figure 10 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to an embodiment of the present disclosure.

[0018] Figure 11 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to another embodiment of the present disclosure.

[0019] Figure 12 This is a concentration distribution diagram illustrating another embodiment of the present disclosure. Figure 11 One example shows the concentration distribution of photoacid and another example shows the concentration distribution of photosensitizer.

[0020] Figure 13 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to another embodiment of the present disclosure.

[0021] Figure 14 This is a concentration distribution diagram illustrating another embodiment of the present disclosure. Figure 13 One example shows the concentration distribution of photoacid and another example shows the concentration distribution of photosensitizer.

[0022] Figure 15 and Figure 16 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device according to another embodiment of the present disclosure.

[0023] The reference numerals in the attached figures are explained as follows: 1A: Semiconductor components 1B: Semiconductor components 10: Measurement Method 101: Base 103: Lower level 201: Photoresist layer 300: Exposure Process 310: First Exposure Process 320: Second Exposure Process 501: Mask PAP: Photonic acid concentration distribution PSP: Photosensitive agent concentration distribution S11: Steps S13: Steps S15: Steps S17: Steps S19: Steps S21: Steps S23: Steps Tg: Glass transition temperature Z: Direction Detailed Implementation

[0024] The following describes specific examples of components and configurations to simplify embodiments of this disclosure. Of course, these embodiments are merely illustrative and are not intended to limit the scope of this disclosure. For example, in the description, a first component is formed on top of a second component, which may include embodiments where the first and second components are in direct contact, or embodiments where an additional component is formed between the first and second components such that the first and second components do not directly contact each other. Furthermore, reference numerals and / or letters may be repeated in many examples of embodiments of this disclosure. These repetitions are for simplicity and clarity and, unless specifically stated herein, do not in themselves represent a specific relationship between the various embodiments and / or the configurations discussed.

[0025] Furthermore, for ease of explanation, spatial relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein to describe the relationship between one element or feature shown in the figures and another element or feature. These spatial relative terms are intended to encompass not only the orientations shown in the figures but also different orientations of the elements during use or operation. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein can be interpreted accordingly.

[0026] It should be understood that when a component is formed on, connected to, and / or coupled to another component, it may include embodiments in which these components are in direct contact, and may also include embodiments in which additional components are formed between these components so that these components are not in direct contact.

[0027] It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, or sections, these elements, components, regions, layers, or sections are not limited by these terms. Rather, these terms are used only to distinguish one element, component, region, layer, or section from another region, layer, or section. Therefore, without departing from the teachings of the inventive concept of the present invention, the first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section.

[0028] Unless otherwise specified herein, when referring to orientation, layout, location, shapes, sizes, amounts, or other measures, terms such as "same," "equal," "planar," or "coplanar" as used herein do not necessarily mean an exact identical orientation, layout, location, shape, size, amount, or other measure, but rather mean, within acceptable differences, substantially identical orientation, layout, location, shape, size, amount, or other measure, for example, that may occur due to manufacturing processes. The term "substantially" may be used herein to convey this meaning. For example, "substantially the same," "substantially equal," or "substantially planar" can mean exactly the same, equal, or planar, or it can be the same, equal, or planar within an acceptable range of differences, for example, which may occur due to the manufacturing process.

[0029] In this disclosure, a semiconductor device generally means a device that can operate by utilizing semiconductor characteristics, and an electro-optic device, a light-emitting display device, a semiconductor circuit, and an electronic device are all included in the scope of semiconductor devices.

[0030] It should be understood that in the description of this disclosure, "above" corresponds to the direction of the Z-direction arrow, while "below" corresponds to the opposite direction of the Z-direction arrow.

[0031] It should be understood that the terms “forming,” “formed,” and “form” can refer to and include any method of creating, building, patterning, implanting, or depositing an element, a dopant, or a material. Examples of forming methods may include, but are not limited to, atomic layer deposition, chemical vapor deposition, physical vapor deposition, sputtering, spin coating, diffusion, deposition, growing, implantation, photolithography, dry etching, and wet etching.

[0032] It should be understood that the functions or steps mentioned in this disclosure may occur in a different order than in the diagrams. For example, two diagrams displayed consecutively may actually be executed approximately simultaneously, or sometimes in reverse order, depending on the functions or steps contained therein.

[0033] Figure 1 This is a flowchart illustrating a method 10 for measuring the critical dimension of a semiconductor element 1A according to an embodiment of the present disclosure. Figures 2 to 5 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device 1A according to an embodiment of the present disclosure. Figure 6 This is a concentration distribution diagram illustrating an embodiment of the present disclosure. Figure 5 The photoacid concentration distribution is shown in the example.

[0034] Please refer to Figure 1 and Figure 2 In step S11, a substrate 101 may be provided, and a lower layer 103 may be formed on the substrate 101.

[0035] Please refer to Figure 2In some embodiments, the substrate 101 may be a bulk semiconductor substrate composed entirely of at least one semiconductor material; the bulk semiconductor substrate does not contain any dielectric, insulating layer, or conductive features. For example, the bulk semiconductor substrate may contain an elemental semiconductor, a compound semiconductor, or a combination thereof, where the elemental semiconductor is such as silicon or germanium, and the compound semiconductor is such as silicon germanium, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, indium antimonide, or other group III-V or group II-VI compound semiconductors.

[0036] In some embodiments, substrate 101 may include an insulator-on-semiconductor structure comprising, from bottom to top, a handle substrate, an insulating layer, and an uppermost semiconductor material layer. The handle substrate and the uppermost semiconductor material layer may contain the same material as the aforementioned bulk semiconductor substrate. The insulating layer may be a crystalline or amorphous dielectric material, such as an oxide and / or nitride. For example, the insulating layer may be a dielectric oxide, such as silicon oxide. As another example, the insulating layer may be a dielectric nitride, such as silicon nitride or boron nitride. As yet another example, the insulating layer may be a stack of a dielectric oxide and a dielectric nitride, such as a stack of silicon oxide and silicon nitride or boron nitride in any order. The insulating layer may have a thickness between approximately 10 nm and approximately 200 nm.

[0037] In some embodiments, the terms "substrate" and "wafer," used interchangeably, both refer to a process performed on a surface or a portion of a surface. Those skilled in the art will also understand that, unless the context clearly indicates otherwise, reference to the substrate may also refer to only a portion of the substrate. Furthermore, reference to deposition on the substrate may refer to a bare substrate and a substrate on which one or more thin films or features are deposited or formed.

[0038] In some embodiments, a plurality of device elements (not shown for clarity) may be formed on the bulk semiconductor substrate or the uppermost semiconductor material layer. Some portions of the plurality of device elements may be formed within the bulk semiconductor substrate or the uppermost semiconductor material layer. The plurality of device elements may be transistors, such as complementary metal-oxide-semiconductor (CMOS) transistors, metal-oxide-semiconductor field-effect transistors (MOSFETs), fin field-effect transistors (FASTs), the like, or combinations thereof.

[0039] Please refer to Figure 2A lower layer 103 may be formed on a substrate 101. The lower layer 103 may be a patterned blanket layer. For example, the lower layer 103 may be a dielectric layer, a barrier layer, an adhesive layer, or an etch stop layer. For example, the dielectric layer may comprise silicon oxide, borosilicate glass, undoped silicate glass, fluorinated silicate glass, a low-dielectric-constant dielectric material, the like, or combinations thereof. The low-dielectric-constant dielectric material may have a dielectric constant less than 3.0 or even less than 2.5. In some embodiments, the low-dielectric-constant dielectric material may have a dielectric constant less than 2.0. These conductive features may be electrically coupled to the device elements.

[0040] In some embodiments, the lower layer 103 may include a plurality of conductive features (not shown for clarity). These conductive features may include a plurality of interconnect layers and a plurality of conductive vias. These conductive features may be electrically coupled to the device elements. In some embodiments, for example, these conductive features may include tungsten, cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper, metal carbides (e.g., tantalum carbide, titanium carbide, magnesium carbide carbon), metal nitrides (e.g., titanium nitride), transition metal aluminum nitrides, or combinations thereof.

[0041] In some embodiments, these device elements and conductive features may be configured together as a plurality of functional units in a first substrate 101. In the description of this disclosure, a functional unit generally refers to a functionally associated circuit that has been divided into distinct units for functional purposes. In some embodiments, these functional units may typically be highly complex circuits, such as processor cores, memory controllers, or accelerator units. In some other embodiments, the complexity and functionality of a functional unit may be more or less complex.

[0042] Please refer to Figure 1 and Figure 3 In step S13, a photoresist layer 201 may be formed on the lower layer 103.

[0043] Please refer to Figure 3For example, the photoresist layer 201 may be an upper coated barrier layer, an upper coated antireflective layer, a lower coated antireflective layer, an imaging layer (photoresist), or a sacrificial and barrier layer (hard mask) for terminating etching. In some embodiments, the photoresist layer 201 may include a solvent, a nonactivated polymer resin, and a photoacid generator (PGA). In some embodiments, the photoresist layer 201 may also include a crosslinking agent, a dye, or other additives.

[0044] In some embodiments, the fabrication technique for the photoresist layer 201 may include a spin coating process. Specifically, during this spin coating process, when... Figure 2 When the described intermediate semiconductor element is rapidly rotated, a photoresist mixture within a solvent carrier can be dispensed onto the surface of the lower layer 103. The intermediate semiconductor element rotates until the solvent carrier is substantially removed, allowing the photoresist mixture to dry into a film of uniform thickness across the entire surface of the lower layer 103. The photoresist mixture may include a photoacid polymer resin and a photoacid generating agent. In some embodiments, the photoresist mixture may also include a crosslinking agent, dye, and / or other additives. In some embodiments, the solvent carrier may, for example, include propylene glycol monomethyl ether acetate, water, or a volatile amine-containing compound.

[0045] Unactivated polymer resin and a photoacid generator can be configured together to form a chemically amplified photoresist system. Typically, the photoacid generator is exposed to a radiation source and converted into a photoacid. The photoacid then excites an activation reaction involving the unactivated polymer resin.

[0046] In the example of a positively chemically amplified photoresist system, photoacid catalyzes the deprotection of the protecting groups on the unactivated polymer resin, increasing the resin's polarity and thus its solubility in the aqueous matrix. Therefore, the activation reaction of a positively chemically amplified photoresist transforms a nonpolar, insoluble polymer resin into a polar, soluble polymer resin.

[0047] In an example of a negative chemical amplification photoresist system, a photoacid reacts with a crosslinking agent to excite crosslinking between adjacent polymer chains. Therefore, the activation reaction of a negative chemical amplification photoresist system converts a single-chain, soluble polymer resin into a crosslinked, insoluble polymer resin.

[0048] It should be understood that volatile byproducts can be generated (or released) in both positive and negative chemical amplification photoresist systems. In some embodiments, for example, volatile byproducts may include propylene glycol monomethyl ether acetate, water, carbon dioxide, alcohols, volatile amine compounds, hydrocarbons, aldehydes, vinyl ethers, and / or sulfides.

[0049] Please refer to Figure 1 and Figure 4 In step S15, a soft baking process can be performed.

[0050] Please refer to Figure 4 During the soft baking process, such as Figure 3 The described intermediate semiconductor element can be heated to near the glass-transition temperature (Tg) of the unactivated polymer resin to remove any remaining solvent carrier from the photoresist layer 201. A curved arrow indicates the removal of the remaining solvent carrier. For example, the additional remaining solvent carrier may include propylene glycol monomethyl ether acetate, water, or a volatile amine-containing compound.

[0051] Please refer to Figure 1 and Figure 4 In step S17, a volatile byproduct generated from the photoresist layer 201 can be monitored.

[0052] Please refer to Figure 4 After the soft baking process, for example, the concentration of volatile byproducts in the chemically amplified photoresist system can be monitored using a gas analyzer. This point in time when volatile byproducts are monitored can be considered the first monitoring of volatile byproducts (e.g., Figure 9 (As shown).

[0053] In some embodiments, for example, the gas analyzer may be a residual gas analyzer (RGA), similar to a device used in vacuum techniques for detecting gas types and their concentrations. The detector of the residual gas analyzer may be any type of mass spectrometer, such as a quadrupole mass spectrometer. Typically, the residual gas analyzer analyzes gases released (or generated) from the photoresist layer 201 (e.g., volatile byproducts) into the atmosphere inside the process chamber by ionizing a portion of the gas molecules in each sample volume and separating the plasma by mass. The residual gas analyzer may rely on a mass sampling technique that monitors only one or more user-selected peak values ​​characterized by the release of gases from the photoresist layer 201. The magnitude of the ion current measured by the residual gas analyzer can be used to determine the concentration (or partial pressure) of the corresponding gas released from the photoresist layer 201.

[0054] In this embodiment, carbon dioxide is monitored. It should be understood that carbon dioxide is a byproduct of the chemical amplification photoresist system after exposure to the radiation source. In other words, theoretically, no signal of carbon dioxide may be detected during this first monitoring period of volatile byproducts. The signal obtained during this first monitoring period of volatile byproducts can be used as a baseline.

[0055] Please refer to Figure 1 , Figure 5 and Figure 6 In step S19, an exposure process 300 can be performed using a mask 501.

[0056] Please refer to Figure 5 Mask 501 can be aimed at Figure 4 The intermediate semiconductor element is described. Mask 501 may include a pattern transferred onto photoresist layer 201. After alignment of mask 201 with the intermediate semiconductor element, exposure process 300 can be performed using a radiation source. For example, the radiation source may be ultraviolet radiation, deep ultraviolet radiation (typically 193 nm and 248 nm), or extreme ultraviolet radiation (typically 13.5 nm). Exposure process 300 may require sophisticated development equipment (e.g., ArF immersion lithography) and precise masking techniques to ensure that radiation is applied precisely only to the portions of photoresist layer 201 intended to be exposed.

[0057] Please refer to Figure 5 and Figure 6 During the exposure process 300, photoacid can be generated from the photoacid generator in the exposed portion of the photoresist layer 201 to form a photoacid concentration distribution PAP, which in Figure 6 The image is enlarged. An example reaction that produces photoacid is shown in equation (1).

[0058] (1)

[0059] Upon exposure to ultraviolet (UV) radiation, the photoacid generator (sulfonium cation) decomposes and provides a proton (photoacid), which can excite an activation reaction involving the unactivated polymer resin. Details of the activation reaction will be described later. In some embodiments, multiple gases (e.g., volatile byproducts) may be generated from the photoresist layer 201 during the exposure process 300. For example, such gases generated from the photoresist layer 201 during the exposure process 300 may include propylene glycol monomethyl ether acetate, water, carbon dioxide, alcohols, hydrocarbons, and / or sulfides.

[0060] Figure 7 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device 1A according to an embodiment of the present disclosure. Figure 8 This is a concentration distribution diagram illustrating an embodiment of the present disclosure. Figure 7 The photoacid concentration distribution is shown in the example. Figure 9 This is a schematic diagram illustrating the concentration curve of volatile byproducts generated from the photoresist layer 201, measured by a gas analyzer, according to an embodiment of this disclosure.

[0061] Please refer to Figure 1 and Figures 7 to 9 In step S21, a post-exposure baking process can be performed, volatile byproducts generated from the photoresist layer 201 can be monitored, and the critical size can be determined based on the monitoring results.

[0062] Please refer to Figure 7 and Figure 8 After exposure process 300, a post-exposure baking (PEB) process can be performed immediately. During the PEB process, Figure 5 The described intermediate semiconductor element can withstand a temperature on the order of the ionization transition temperature (Tg) of the unactivated polymer resin. The thermal energy applied to the photoresist layer 201 during the post-exposure baking process can cause photoacids to diffuse into the photoresist layer 201, forming a structure such as... Figure 8 The magnified view shows the photoacid concentration distribution PAP. The diffusion of photoacid can fully activate the unactivated resin in the regions exposed to the radiation source, and can also suppress any standing wave effect at the edges of the exposed regions of the photoresist layer 201. The photoacid activation reaction is illustrated by equations (2) to (4).

[0063] (3) (4) In equation (2), photoacids can cause the unactivated polymer resin (insoluble) to convert into a soluble product containing polar hydroxyl groups. The unstable leaving group may spontaneously decompose and produce byproducts as shown in equations (3) and (4), such as carbon dioxide, isobutylene, and protons. The protons produced by the decomposition of the leaving group can further catalyze the conversion of the unactivated polymer resin. In some other embodiments, other byproducts may also be produced during the post-exposure baking process, such as propylene glycol monomethyl ether acetate, water, carbon dioxide, alcohols, volatile amine compounds, hydrocarbons, aldehydes, and / or vinyl ethers.

[0064] Please refer to Figure 9 The concentration of reaction byproducts (e.g., carbon dioxide in an illustrative reaction) can be monitored as a function of time to determine the endpoint of the post-exposure baking process. For example, when the activation reaction reaches a process endpoint, the level of byproducts may decrease, making it possible to detect the endpoint of the post-exposure baking process. In other words, the process duration of the post-exposure baking process is based on chemical changes that occur in lieu of a fixed process time. As another example, the endpoint of the post-exposure baking process can be determined by the rate of change of concentration (e.g., the slope of the concentration curve or the first derivative of the concentration curve), the second rate of change (e.g., the second derivative of the concentration curve), or a combination thereof. The time point at which the endpoint of the post-exposure baking process is reached, used to monitor volatile byproducts, can be represented as a second monitoring of volatile byproducts.

[0065] In some embodiments, the difference between the concentrations measured at the first monitoring point and the second monitoring point of the volatile byproducts can be used to obtain the critical size of the patterned photoresist layer 201 after the development process described later.

[0066] In some embodiments, a cooling process may be performed after the post-exposure baking process to cool the material as follows: Figure 7 The intermediate semiconductor element is described. Volatile byproducts can be monitored after the cooling process. The time point at which volatile byproducts are monitored after the cooling process can be represented as the third monitoring of volatile byproducts.

[0067] In some embodiments, volatile byproducts can be continuously monitored from the first monitoring of volatile byproducts to the third monitoring of volatile byproducts. After the development process, the integral of the concentration profile from the first monitoring of volatile byproducts to the third monitoring of volatile byproducts can be used to obtain the critical size of the patterned photoresist layer 201.

[0068] In some embodiments, depending on the chemically amplified photoresist system used, activation of the polymer resin can primarily occur during exposure process 300 or the post-exposure baking process. Many chemically amplified photoresists are high activation energy systems, and such photoresists include, for example, T-Boc protected by the polymer resin described in the illustrative activation reaction. This means that even during exposure process 300, photoacid (H+) is generated by a photoacid generator. + After that, additional heat energy is required to initiate activation. The heat energy is provided by the post-exposure baking process. In this case, monitoring of volatile byproducts can be performed before the exposure process 300 (e.g., the first monitoring of volatile byproducts) and after the post-exposure baking process (e.g., the second or third monitoring of volatile byproducts).

[0069] In some embodiments, such as other chemically amplified photoresist systems that utilize acetal protection, they are low activation energy systems. This means that once photoacid (H) is generated by the photoacid generator during exposure process 300, + Significant activation of the polymer resin can occur even without additional heat. In this case, monitoring of volatile byproducts can be performed before and after exposure process 300.

[0070] It should be understood that Figure 9 The concentration curves provided are for illustrative purposes and do not necessarily represent an actual concentration curve. An actual concentration curve will vary depending on the specific pattern formed in the photoresist layer 201, the specific type of photoresist used, and the thickness of the photoresist layer 201.

[0071] Figure 10 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of a semiconductor device 1A according to an embodiment of the present disclosure.

[0072] Please refer to Figure 1 and Figure 10 In step S23, a developing process can be performed.

[0073] Please refer to Figure 10 During the development process, an aqueous base (alkaline solution) can be added to the photoresist layer 201 during exposure and baking, and can dissolve a portion of the resin. Depending on whether the chemically amplified photoresist system is positive or negative, activated or unactivated polymer resin can be dissolved in the aqueous base and removed.

[0074] Following the aforementioned processing, the carefully created photoresist pattern on the photoresist layer 201 can be used to selectively mask the etching of the underlying layer (e.g., the underlying layer 103) to form multiple semiconductor structures with extremely precise shapes and sizes.

[0075] Typically, critical dimension (CD) measurements are performed using a scanning electron microscope (SEM) employing multiple electron beams. However, these electron beams can damage the photoresist, limiting CD-SEM measurements to multiple dummy marks specifically designed and located on scribe lines. In other words, CD-SEM cannot measure the CD of an actual pattern within a functional unit. Furthermore, argon fluoride lithography (ArFi), which uses a chemically amplified photoresist system, is even more susceptible to the effects of these electron beams. During the initial measurement, the CD may shrink significantly, resulting in substantial CD measurement bias. Therefore, it is difficult to determine the actual CD (before damage).

[0076] Conversely, determining the CD of the patterned photoresist layer 201 by using the concentration difference between the first and second monitors of volatile byproducts, or by using the concentration integral from the first to the third monitor of volatile byproducts, can be non-destructive to the pattern. That is, the CD of the actual pattern can be measured. This also implies the elimination of virtual markers for measurement, saving space for metrology and providing more space for multiple functional circuits.

[0077] Furthermore, the actual pattern of CD can be verified using physical failure analysis (PFA) methods, such as transmission electron microscopy (TEM). After verifying the PFA, the correlation between TEM data and CD determined by monitoring volatile byproducts can be established. In this case, the CD determined by monitoring volatile byproducts can be used as a standalone standard for CD measurement. Therefore, the processing capability of CD measurement can be improved.

[0078] In some embodiments, the residual gas analyzer may be small enough to collect volatile gases only within a specific region. This region may be an area of ​​an actual pattern contained in a grain, a single grain region within a wafer, some grains within a wafer, or the entire wafer.

[0079] In some embodiments, a spin coating process, an exposure process 300, a post-exposure baking process, and a development process can be performed in a lithography system. A residual gas analyzer can be integrated into the post-exposure baking module of the lithography system. For example, the residual gas analyzer can be installed anywhere along the exhaust line of the lithography system and coupled to the exhaust pipe of the lithography system.

[0080] Figure 11This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of semiconductor element 1B according to another embodiment of the present disclosure. Figure 12 This is a concentration distribution diagram illustrating another embodiment of the present disclosure. Figure 11 One example shows the concentration distribution of photoacid and another example shows the concentration distribution of photosensitizer.

[0081] Please refer to Figure 11 The photoresist layer 201 may include an unactivated polymer resin, a photoacid generator, and a photosensitizer generator. The unactivated polymer resin, photoacid generator, and photosensitizer generator are configured together to form a photo-sensitized chemical amplification photoresist system, which requires a two-step illumination process to generate photoacid.

[0082] Please refer to Figure 11 and Figure 12 In a photosensitive chemical amplification photoresist system, a first exposure process 310 can be performed. During the first exposure process 310, a radiation source of a first wavelength can expose the photoresist layer 201 via a mask 501 to form multiple exposed areas and multiple unexposed areas inside the photoresist layer 201. During the first exposure process 310, a photosensitive agent (PS) is generated from the photosensitive agent generator in the exposed areas of the photoresist layer 201 to form... Figure 12 The magnified photosensitive agent concentration distribution (PSP).

[0083] Depending on the chemical composition of the photosensitive chemical amplification photoresist system, in some embodiments, photoacids can be formed from photoacid generators located inside the exposure areas of the photoresist layer 301 during the first exposure process 310, to form a... Figure 12 The amplified photoacid concentration distribution PAP is shown in the image. In this case, monitoring of volatile byproducts can be performed (or started) before the first exposure process 310.

[0084] In other embodiments, there is no overlap between the mildly sensitive range of the photosensitizer and the mildly sensitive range of the photoacid generator, so that no photoacid is generated during the first exposure process 310. In this case, monitoring of volatile byproducts can be performed (or started) after the first exposure process 310.

[0085] In some embodiments, electron beam (eBeam), KrF (krypton fluoride), or ArF (argon fluoride) exposure can be used in the first exposure process 310.

[0086] Figure 13 This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of semiconductor element 1B according to another embodiment of the present disclosure. Figure 14 This is a concentration distribution diagram illustrating another embodiment of the present disclosure. Figure 13 One example shows the concentration distribution of photoacid and another example shows the concentration distribution of photosensitizer.

[0087] Please refer to Figure 13 and Figure 14 A second exposure process 320 can be performed on the photoresist layer 201. During the second exposure process 320, a radiation source of a second wavelength, different from the first wavelength, can expose the photoresist layer 201 without any masking. In other words, the second exposure process 320 is a flood exposure process. The chemical composition of the photosensitive chemical amplification photoresist system is selected so that the photosensitizer is sensitive to the second wavelength used in the second exposure process 320, while other photoresist components are insensitive. Therefore, the radiation source of the second wavelength can amplify the photosensitizer generated in the previously exposed (i.e., unmasked) areas, thereby amplifying the photoacid generated from nearby photoacid-generating agent molecules, thereby forming on the photoresist layer 201. Figure 14 The photoacid concentration distribution (PAP) in the image shows a higher peak value, thus exhibiting better contrast.

[0088] It should be understood that even with full exposure (i.e., the second exposure process 320), unlike a conventional full exposure process, no photoacid is generated in the unexposed (masked) areas during the first exposure process 310, therefore there is no DC bias and high contrast is maintained. This is because, in a photosensitive chemical amplification photoresist system, the generation and amplification of photoacid only occur in the presence of the photoresist.

[0089] and Figure 12 Compared to the photosensitive concentration distribution (PSP) in the first exposure step 320, the PSP may change slightly after the second exposure step 320, but may change significantly in some chemical embodiments.

[0090] In some embodiments, the first wavelength may be less than 300 nm, while the second wavelength may be greater than 300 nm or approximately 365 nm.

[0091] In some embodiments, an additional heating or baking process may be inserted between the first exposure process 310 and the second exposure process 320 to mitigate the extreme ultraviolet shot noise effect of the first exposure process 310. For example, a heating process may be used between the first exposure process 310 and the second exposure process 320 to diffuse the photosensitizer and smooth the photosensitizer concentration distribution (PSP) affected by the extreme ultraviolet shot noise effect.

[0092] Figure 15 and Figure 16This is a cross-sectional schematic diagram illustrating a portion of the process for measuring the critical dimensions of semiconductor element 1B according to another embodiment of the present disclosure.

[0093] Please refer to Figure 15 The baking process after exposure can be similar to Figure 7 The procedure described herein will not be repeated here. The post-exposure baking process can also activate the conversion of unactivated polymer resins. In this case, monitoring of volatile byproducts can be performed (or terminated) after the post-exposure baking or cooling process.

[0094] In some embodiments, when using a photosensitive chemical amplification photoresist system, the post-exposure baking process can be omitted. In this case, monitoring of volatile byproducts can be performed (or terminated) after the second exposure process 320.

[0095] Please refer to Figure 16 The developing process can be similar to, for example Figure 10 The program described herein is implemented therein, and its description will not be repeated in the text.

[0096] One embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate; monitoring a volatile byproduct generated from the photoresist layer to obtain a first quantity of the volatile byproduct; exposing the photoresist layer to a radiation source; monitoring the volatile byproduct generated from the photoresist layer to obtain a second quantity of the volatile byproduct; and obtaining the critical size based on the difference between the first quantity and the second quantity of the volatile byproduct.

[0097] Another embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate; exposing the photoresist layer to a radiation source; heating the photoresist layer; continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point at which the photoresist layer is formed on the substrate to a second time point after the photoresist layer is heated to obtain a concentration curve of the volatile byproduct; and obtaining the critical size based on the integral difference of the concentration curve between the first time point and the second time point.

[0098] Another embodiment of this disclosure provides a method for measuring a critical size, comprising: providing a substrate; forming a photoresist layer on the substrate, wherein the photoresist layer includes a solvent, an unactivated polymer resin, a photoacid generator, and a photosensitizer generator; exposing the photoresist to a radiation source at a first wavelength; exposing the photoresist to a radiation source at a second wavelength, the second wavelength being different from the first wavelength; heating the photoresist layer; continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point after the formation of the photoresist layer on the substrate to a second time point after heating the photoresist layer to obtain a concentration curve of the volatile byproduct; and obtaining the critical size based on the integral difference of the concentration curve between the first time point and the second time point. The photosensitizer generator is sensitive to the second wavelength, while the photoacid generator is not sensitive to the second wavelength.

[0099] Due to the design of the critical dimension measurement method disclosed herein, the critical dimension of the actual pattern can be measured without any damage from the volatile byproducts generated from the photoresist layer 201. Furthermore, there is no need for dummy marks used for metrology. This saves the area previously occupied by dummy marks used for metrology. Therefore, more physical space can be provided for multiple functional circuits, thereby reducing costs.

[0100] While this disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions, and alternatives may be made without departing from the spirit and scope of this disclosure as defined in the claims. For example, many of the processes described above may be implemented using different methods, and other processes or combinations thereof may be substituted for many of the processes described above.

[0101] Furthermore, the scope of this application is not limited to the specific embodiments of the processes, machinery, manufacturing, material composition, means, methods, and steps described in the specification. Those skilled in the art will understand from the disclosure of this publication that existing or future processes, machinery, manufacturing, material composition, means, methods, or steps that have the same function or achieve substantially the same results as the corresponding embodiments described herein can be used based on this disclosure. Therefore, such processes, machinery, manufacturing, material composition, means, methods, or steps are included within the scope of the claims of this application.

Claims

1. A method for measuring a critical dimension, comprising: Provide a base; A photoresist layer is formed on the substrate, wherein the photoresist layer includes a solvent, an unactivated polymer resin, a photoacid generator, and a photosensitizer generator; The photoresist layer is exposed to a radiation source of a first wavelength. The photoresist layer is exposed to a radiation source at a second wavelength, which is different from the first wavelength. Heating the photoresist layer; A concentration profile of the volatile byproducts generated from the photoresist layer is obtained by continuously monitoring a volatile byproduct generated from the photoresist layer from a first time point after the photoresist layer is formed on the substrate to a second time point after the photoresist layer is heated. as well as The critical size is obtained based on the integral difference of the concentration curve between the first time point and the second time point; The photosensitizer is sensitive to the second wavelength, while the photoacid generator is not sensitive to the second wavelength.

2. The method for measuring critical dimensions as described in claim 1, wherein the first wavelength is less than 300 nm and the second wavelength is greater than 300 nm.

3. The method for measuring critical dimensions as described in claim 2, wherein the solvent comprises propylene glycol monomethyl ether acetate, water, or a volatile amine-containing compound.

4. The method for measuring critical dimensions as described in claim 1, wherein the volatile byproducts include carbon dioxide, propylene glycol monomethyl ether acetate, water, alcohols, volatile amine compounds, hydrocarbons, aldehydes, vinyl ethers and / or sulfides.

5. The method for measuring critical dimensions as described in claim 4, further comprising performing a soft baking process between forming the photoresist layer on the substrate and exposing the photoresist layer to the radiation source of the first wavelength.

6. The method for measuring critical dimensions as claimed in claim 5, wherein performing the soft baking process includes heating the photoresist layer to a glass transition temperature of the unactivated polymer resin.

7. The method for measuring the critical size as described in claim 6, wherein continuous monitoring of the volatile byproducts generated from the photoresist layer is achieved by means of a residual gas analyzer.

8. The method for measuring critical dimensions as claimed in claim 7, wherein the residual gas analyzer is integrated into a post-exposure baking module of a lithography system.

9. The method for measuring the critical size as described in claim 8 further includes establishing a numerical correlation between the critical size obtained from the integral difference of the concentration curve between the first time point and the second time point and multiple physical failure analysis results.

10. The method for measuring the critical dimension as described in claim 9, further comprising performing a development process after heating the photoresist layer.

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